Table 1.

Symptom grade of orthostatic intolerance

Grade I Orthostatic symptoms are infrequent, inconstant, or only under conditions of increased orthostatic stress Standing time typically ≥15 minutes Unrestricted activities of daily living Blood pressure indices may or may not be abnormal

Grade II Orthostatic symptoms are frequent, developing at least once a week. Orthostatic symptoms commonly develop with orthostatic stress Standing time ≥5 minutes on most occasions. Some limitation in activities of daily living. Some change in cardiovascular indices. These might be OH, reduction in pulse pressure ≥50%, excessive oscillations in BP.

Grade III Orthostatic symptoms develop on most occasions, and are regularly unmasked by orthostatic stressors. Standing time ≥1 minute on most occasions. Marked limitation in activities of daily living. Orthostatic hypotension is present on ≥50% of the time, recorded on different days.

Grade IV Orthostatic symptoms consistently present. Standing time <1 minute on most occasions. Patient is seriously incapacitated, being bed- or wheel-chair bound because of orthostatic intolerance. Syncope/presyncope is common if the patient attempts to stand. Orthostatic hypotension is consistently present.